Advancing coating strategies for enhanced corrosion resistance, interfacial contact, and performance of metallic bipolar plates in proton exchange membrane fuel cells

This study presents a comprehensive performance analysis of aluminum titanium nitride (AlTiN) and aluminum chromium nitride (AlCrN) coatings applied to stainless steel 316L (SS316L) stainless steel substrates, evaluating their potential as metallic bipolar plates in proton exchange membrane fuel cells (PEMFCs). The coatings were deposited using the cathodic arc physical vapor deposition (CA-PVD) technique. Extensive material characterization revealed significant improvements in key properties, including a reduction in interfacial contact. The corrosion resistance of AlTiN- and AlCrN-coated SS316L bipolar plates was evaluated under simulated PEMFC conditions. Both coatings exhibited corrosion current densities below the US DOE 2025 target of 1 µA cm⁻², confirming excellent electrochemical stability, alongside increased hydrophobicity. Adhesion tests confirmed the stability of both coatings, achieving a top rating of grade 5B. Single-cell fuel cell testing demonstrated a notable improvement in performance, with AlTiN-coated plates exhibiting an 18.59% increase in peak power density 12.452 mW per cm² compared to uncoated SS316L plates at 10.5 mW per cm², outperforming the AlCrN-coated plates. These findings highlight AlTiN as a promising coating material for enhancing the durability and efficiency of PEMFCs, suggesting potential for further optimization through advanced membrane electrode assembly MEA configurations.